The invention relates to a pusher furnace with rails and with sliding shoes which are guided displaceably on these and carry the treatment material to be transported through the furnace, sliding supports which have grooves for receiving material abrasion being provided on the rails.
Pusher furnaces are used mostly for the annealing treatment of bars, for example aluminium bars. Bars of this type may weigh several tons and are therefore usually moved with the aid of hydraulic pusher devices.
EP 0 108 047 B1 discloses a pusher furnace, the rails of which are provided with a multiplicity of sliding elements. These sliding elements are inserted, each sliding element separately, into shallow recesses, lying one behind the other and next to one another, on the surface of the rails and project out of the surface of the rails. These sliding elements may have surface grooves, running obliquely to the rail longitudinal direction, for receiving material abrasion. The plate-shaped sliding elements form, with their short sides which are produced perpendicularly to the rail longitudinal direction, smooth butt edges to the sliding shoes displaceable on the sliding elements. Butt edges which are so smooth are disadvantageous, since, when the sliding shoes strike these edges, jolt-like movements may occur and consequently critical loads on the sliding shoes and sliding elements. If the sliding elements are mounted above the joint region of two rails, there is the risk of fracture. A further disadvantage of the above version is that rails and sliding elements have to be produced separately and a multiplicity of sliding elements per rail have to be fastened in a complicated way, for example by means of screws.
The object of the present invention, then, is to provide a pusher furnace of the type mentioned in the introduction, which, along with a simple construction, allows a jolt-free displacement of sliding shoes subjected to high load.
According to the invention, therefore, it is proposed to produce the pusher furnace in such a way that the sliding supports are of plate-shaped design, these in each case fully cover the rails over their width and are provided on their top sides with grooves, running in an arrow-shaped manner in the longitudinal direction of the rails, for receiving material abrasion, and in such a way that a plurality of sliding supports are lined up with one another to form arrow-shaped joints, the cross section of the joints corresponding essentially to that of the grooves. By sliding elements being designed to cover the entire rail width and to have arrow-shaped grooves, jolt-like impacts when sliding shoes strike sliding elements are markedly reduced. Moreover, by means of arrow-shaped joints, a wide transitional region is provided, in which one rail can scarcely be displaced laterally in relation to another. Jolt-like impacts on account of height differences between two rails are mitigated by the arrow-shaped transitional region. The durability of rails and sliding shoes can thereby be markedly increased.
According to the invention, furthermore, there is provision for the sliding supports to be capable of being screwed to the rails. This screw connection is appropriate, in particular, where high-grade sliding supports are concerned. Thus, if required, only the sliding support which is worn in each case is renewed.
According to the invention, furthermore, there is provision for the rails and the sliding supports to be capable in each case of being connected to one another in one piece.
According to the invention, furthermore, there is provision for the rails and the sliding supports to be capable in each case of being connected to one another in one piece as a casting. The one-piece construction, for example in the form of a casting, makes simple production, assembly and disposal possible.
According to the invention, furthermore, there is provision for the sliding supports to be capable of being made of cast steel.
Finally, the pusher furnace may be designed in such a way that the tips of the arrow-shaped grooves of the sliding supports are directed towards the direction of transport. The reception and discharge of material abrasion are thereby improved.